Another place to get organic whole corn is Azure Standard (www.azurestandard.com). I don't know where you are located, but they have lots of bulk staples like this. If you live near one of their truck routes, you can get free shipping with a group order totalling $400.00.

We actually use popcorn in our grain mill to make cornmeal. It's a bit harder to grind but the taste is awesome. The only issue we've found in using it is that it's got more bran than regular dried corn, which you can sift out if you're picky about that sort of thing. But since dried corn is very difficult to find in most stores that sell organic bulk foods and we don't go through enough dried corn to warrant buying a big bag of it to store, then we just buy the organic popcorn and grind that instead.